IDUs appear to be at particular high risk for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) infections, suggesting the need for an intervention that addresses them simultaneously while clarifying how they differ. The prevalence of HCV among IDUs ranges from 60% to 80% in most cities. Injecting drug users are at increased risk of all three viral infections through the direct and indirect sharing of injection equipment and through unprotected sexual behavior. Due to the heterogeneity in risk behaviors and infection status among IDUs, interventions need to be personalized by tailoring them to these characteristics. This revised 4.5-year community- based field experiment will enroll 840 out-of-treatment IDUs into a two-group design. More specifically, it will compare the outcomes, cost, and cost-effectiveness of a standardized six-session educational intervention that addresses HIV, HCV, and HBV to those of a six-session motivational intervention that includes a personalized risk assessment and motivational interviewing tailored to each participant's stage of change, gender, personal risk profile, and serostatus. The personal risk profile will be computer generated from assessment data. The computer will also be programmed to present specific intervention cue-cards/slides in response to each participant's unique profile of HIV, HCV, and HBV test results. Hypotheses will be tested to determine intervention impact on the 6- and 12-month outcomes. The specific aims of the proposed study are: Aim 1: To compare the effectiveness of a 6-session personalized motivational intervention to a 6-session educational intervention in terms of injection risk, sexual behavior, alcohol use and knowledge and perception related to HBV and HCV. Aim 2: To estimate the cost and cost-effectiveness of a 6-session personalized motivational intervention relative to a 6-session educational intervention. This proposed study builds upon the personalized and motivational interventions shown to be effective in our previous studies with out-of-treatment substance abusers, and the pilot test of the proposed intervention that demonstrated short-term change in risk behaviors. We believe the significance of the proposed study arises from the need to reach out-of-treatment IDUs to determine their HIV/HBV/HCV serostatus, educate them on each disease, prevent new infections among those who are not infected, and slow disease progression among those already infected. We believe the innovation of the proposed study lies in its personalized motivational intervention tailored to each IDUs unique combination of HIV, HCV, and HBV test results.